The present invention relates to a method in a sequential bending furnace for bending glass sheets. A furnace for applying the method includes a sequence of successive sections, at least some of which are provided with heating elements for applying a thermal effect to a glass sheet to be bent for heating and bending it sequentially in the sections. The furnace is further provided with a sequence of successively arranged carriages or the like, fitted with wheels or other conveying elements and mounted on a transfer track or a like. The glass sheets to be bent are laid to be supported by bending molds or the like associated with the carriages or the like. The furnace is further accompanied by a transfer mechanism for carrying the carriages or the like simultaneously forward in the furnace into a section further away in the advancing direction of the carriages for the next bending operation.
As for the prior art, reference is made e.g. to Finnish patent 68390. This patent discloses a solution which is essentially consistent with the presently known state of the art.
The present invention is particularly a result of the ever increasing demands set on the current production technology. The currently applied production technology requires an improved smoothness for and control over movements of the carriages as well as an extremely precise parking accuracy. In particular, the carriages may not be allowed to move during the bending cycles effected in the sections. In addition, especially the transfer mechanism must be readily serviceable without interfering with the actual bending process. It is especially the demands for parking accuracy as well as for preventing the uncontrolled movements of carriages during the bending sequences effected in the sections which require that a thermal expansion effect caused by temperature fluctuations must not interfere with operation of the transfer mechanism or parking accuracy of the carriages. The above problems are abundant in sequential bending furnace designs according to the prior art. Thus, as a whole, the production technology is far from being controlled and continuous to the extent required by the investments made in production technology or engineering.